Hydraulic servo-mechanism



Dec. 22, 1964 H. zoLLER HYDRAULIC SERVO-MECHANISM Filed June 9. 1961 United States Patent O 3,162,693 HYERAUUC SERVG-MECHANKSM Hans Zller, deceased, late ot Lauhenheini, naar Mainz, Germany, by Elisabeth Katharina Zller, ne Kehl, and Helga Schulz-Zller, ne Zller, heirs, both of tl-6ti Wormserstrasse, Laubenheim, near Mainz, Germany Filed .lune 9, i961, Ser. No. .6,662 2 Claims. (Cl. 91--3tl6) This invention relates to iuid driven engines and methods ot operating them in which a piston is driven alternately from two sides by a liuid under pressure. More particularly the invention concerns a special main control valve in a feed system for such an engine.

An object of the present invention is to provide a system for driving a double action engine which is operated by a pressure medium. Such a pressure medium may be a fluid under pressure, such as a liquid or a compressed gas (which may be air or steam, for example), which constitutes the working fluid or propellant for the working piston.

According to the present invention a system is provided which comprises (1) a source of pressure medium, worlcing luid or propellant; (2) a pressure engine provided with a working piston operating within a cylinder; (3) a plurality of pressure medium conduits, pipes, tubes or ducts which provide connections between the pressure medium source and the cylinder; (4) a plurality of valves inserted in selected conduits and in particular at least one main control valve operated by dilterential pressure; (5) and finally means for switching the entire system on and off which may be a manually operated switch Valve.

The main control valve system comprises a number of pressure medium or uid chambers or compartments which convey the working iuid successively alternately to the iirst and thereafter the second side of the piston of the control valve. This valve is controlled by two secondary operating valves allocated respectively to the first side and the second side of the working piston.

Another object of the invention is to provide, in a system of the kind described, a single main control valve which is actuated by the system itself and is therefore automatic in response to differential feed back pressure. The valve system of the main valve contains several pressure medium chambers, One chamber is a propellant inlet chamber which is always in communication either with a rst or with a second connecting chamber. The two connecting chambers communicate respectively with the cylinder on either side of the piston.

Further objects, features and advantages of the invention appear in the following detailed description of a preferred embodiment of the invention taken together with the drawing. The drawing and detailed example are provided by way of illustration and not of limitation.,

Construction In the drawing, a pressure medium source T, such as a compressed air tank, is connected to the system by a pipe l. The pipe i contains a manually operated shut-off valve or switch 2 which may be constructed as a three-way valve. It may be arranged so that it shuts oli the pipe il from the rest of the system or so that it connects the entire system to an exhaust aperture E..

A principal component of the system is a main control valve M. A main valve control piston or slider 4 is mounted in a housing 3 of the main valve M so that it can move longitudinally. As seen at the top of the drawing, the main valve piston 4 has on its upper extremity a rst piston head P1 provided with a packing ring 5, which move together in a lirst cylinder chamber C1. other end the valve piston 4 extends to form a second head P2 which projects into a second cylinder chamber C2 of the housing. The cross sectional area of the second head P2 is smaller than that of the piston head P1.

Within the housing 3 of the main valve M are tive tluid chambers l, CCl, CC2, O1 and O2. These are arranged in line adjacent one another and are sealed by packing rings 3l, 32, 33, 34 and 35 respectively. The packing rings are mounted in circumferential grooves in and arranged in a :fixed position with respect to the inner surface of the wall of the housing 3; their inner annular surfaces engage closely and seal with the enlarged parts of the main valve piston fl.

The chambers are arranged as follows:

A fluid inlet chamber I is arranged as a central or intermediate chamber and is connected, via the main uid conduit 9, the manually operated on-oi valve 2, and the feed pipe l, with the source T of pressurized fluid. The connecting chambers CCI and CC2 are situated on each side of the inlet chamber I and are separated from the inlet chamber I solely by the respective packing ring 32 or 33.

The lirst connecting chamber CO1, is joined by the pipe 37 with the engine working cylinder 14 on one side of the working piston l5; while the second connecting chamber CC2 is joined by the pipe 1li with the cylinder 14 on the other side of the piston 15.

Adjacent to the first connecting chamber CC1, and separated from it by the packing ring 3l is the rst iiuid outlet chamber O1. A vent 1l of this chamber is always connected with the external atmosphere, or in the case of a hydraulic system with a collection sump for the liquid. Similarly, the second uid outlet chamber O2 is provided adjacent the second connecting chamber CC2 and is separated from it by a packing ring 34.

Adjacent the first outlet chamber O1 is the rst valve operating cylinder C1 of the main control valve M. The chamber O1 Vand cylinder C1 are separated by a guide ring G. The ring G provides a path for the fluid between the cylinder C1 and the chamber O1. The outer surface of the guide ring G is inserted in a circumferential groove provided in the inner surface of the wall of the housing 3 and so is secured to the cylinder wall.

The second outlet chamber 02 is isolated from the adjacent second cylinder C2 by a packing ring 3S. When the manual valve 2 is switched on, the second cylinder C2 is always connected with the fluid source T by the duct 36 which is a branch of the main conduit 9.

The control piston or slider 4 of the main valve M has two recessed zones A1 and A2 of reduced cross section between two enlarged longer zones B1 and B2 and a shorter enlarged central zone B3.

T he first outer enlarged zone B1 acts with the sealing ring 3l and in the operating position of the valve piston 4 (not shown in the drawing) engages the ring 31 with a sealing eiifect.

The second outer zone B2 of enlarged cross section acts with the rings 3d and 35 and constantly engages the ring At its 35. In the position of the valve slider Il (which is not shown in the drawing) this zone, B2, disengages the ring 34.

The central enlarged zone B3 cooperates with the rings 32 and 33. In the operating position of the control valve slider 4 (not shown in the drawing) this Zone B3 releases the ring 32 and engages the ring 33.

Auxiliary operating valves D1 and D2 are provided for control of the main valve M. The iirst operating valve D1 is situated on one side of the working piston 15 and its control pin 18 projects into the inner chamber of the cylinder 14. The control pin 18 is held and moves in the packing 2t). The packing ring 21, together with the rear part of the control pin 18, separates the internal chamber of the valve D, into two compartments of which the rear or right one -is connected with the main conduit 9 by the pipe 23. The control pin 18 is held in the position in which the two compartments are separated by a spring 22. The pin 18 is provided with a portion of reduced thickness in order to allow the two compartments to be joined when the pin 1S is pressed in to the right.

The operating valve D2, allocated to the left or second side of the working piston 15, is constructed in what is basically the same manner as the valve D1. lt is provided with a control pin 26, a main packing 27, a packing ring 28, which subdivides the valve into two compartments, and a spring 29. The rear compartment of the second operating valve D2 is connected by a conduit 24 to the front chamber of the rst operating valve D1, and by a pipe 25 to the rst cylinder C1 of the main control valve M. The front compartment of the second operating valve D2 connects by vents 30 with the atmosphere or with a sump.

The circumferential portions of packing rings 2b, 2l, 27 and 28 are inserted into grooves at the inner surface of the valve housing wall. They are thus fixed with respect to the valve housing. The valve pins 13 and 26 are guided for axial sliding by packing rings 20, 21 and 27, 2S respectively.

A pump, valve, or switch to be driven may be attached to the working piston 15.

Operation When the ori-olf valve 2 is open fluid flows through the conduits 1, 9, 23 and 36. When the main valve slider or piston 4 is in its top position, as seen in the drawing, the fluid owing through the conduit 9 flows past the packing 33 along the recess A2 of the valve piston 4, through the conduit 1? into the working cylinder 14 and moves the piston to the right.

The piston 15 forces the pin 18 to the right against the spring 22 and against the pressure of the iiuid coming from the conduit 23. Fluid then flows past the packing 21 in the valve D1 and via the conduits 24 and 25 to the piston head P1 of the main valve slider or piston 4 in the cylinder C1. This forces the latter down, so that the packings 31 and 33 seal chambers CC1 and I.

The packings 32 and 34 are disengaged so that fluid liowing out of conduit 9, goes past the packing 32 along the constriction A1 and via the conduit 37, to the cylinder 14, forcing the piston v15 to the left. In this process, the exhaust fluid, from the piston 15, flows out via the conduit 1@ into chamber CCE, past the packing 34 along the constriction Azand out at 11.

When the piston 15 engages the pin 26, the pin 26 moves to the left against the spring 29 so that fluid in the cylinder C1 ilows past the packing 28 and exhausts at 3l?. The iiuid from conduit 36 acts from below through chamber C2 on the surface of the valve piston 4, forcing it up together with its seating 5 so that packings 32 and 34 are engaged as in the drawing, while packings 31 and 33 release the valve at the recesses. Again iluid llows along conduit 37 to the left past the packing 31 and out at the upper vent 1l, as duid from conduit 9 ilows past the packing 33 and via conduit 10 enters the working cylinder 14 and forces the piston 15 to the right as seen in the drawing.

The operating cycle described repeats regularly and as long as the switch valve 2 is open: The piston 15 moves in the cylinder i4 alternately left and right until reversal occurs in each case via the secondary valve pins 18 and 26 and the main valve piston 4.

What is claimed is:

1. A main control slide valve which is operated by differential pressure for operating a pressure-medium engine, of which the working piston is fed and driven by a pressure-medium from two sides in alternation during the working strokes, comprising at least three stationary valve chambers formed by an annular space between the outer surface of the full diameter zones of a slide valve having two zones of constricted diameter and the inner surface of a cylindrical valve housing, said stationary valve chambers being arranged side by side along the longitudinal axis of said cylindrical valve housing and being separated from each other by packing rings secured to the inner surface of the valve housing and alternately engaged and released by said full diameter zones of the slide valve so that chambers which are in communication in a first slide position are separated in the second position and vice versa; and differential pressure means to move said slide valve between said two positions comprising a iirst piston head of enlarged cross section on a first end of said control slide valve, which piston head works in a iirst operating chamber of said valve housing and a second piston head of smaller cross section on a second end of said control slide, which second piston head works in a second operating-chamber of said valve housing and means independent from said pressure inlet of the valve which connect said second operating-cylinder directly with pressure-medium piping at all times and which connect said iirst operating-cylinder selectively with said pressure medium inlet valve and with said second operating-cylinder via valves, and connect selectively with said pressure-medium piping and with a pressure-medium vent.

2. In a system for driving an engine in which a working piston is supplied with a pressurized fluid alternately from each side, and which comprises: a source of uid under pressure; an engine including a piston moving in a working cylinder; a plurality of fluid conduits, including a main conduit connecting said source and said working cylinder; and a plurality of valves arranged in working relation with at least one of said conduits; the improvement comprising a main iluid valve having a valve piston sliding in a cylinder between two end positions to conneet alternately each side of said working piston with said main conduit; said slide valve piston having two zones of constricted diameter and three zones of full diameter, said valve piston forming an annular space with the inner surface of the valve housing along its entire length, said annular space being divided into iive stationary chambers within said housing separated from each other by packing rings which are secured to the inner surface of the valve housing and alternately engaged and released by said full diameter zones of the valve pistons; said live stationary pressure-medium chambers comprising a pressure-medium inlet-chamber, a iirst pressuremedium connecting-chamber which is situated on one side of and is connected with a working cylinder on a first side of a working piston, a second pressure-medium connecting-chamber which is situated on a second side of and opposite said iirst pressure-medium connecting-chamber and is connected with said working cylinder on a second side of said working piston, a first pressure-medium outletchamber which is situated opposite said pressure-medium inlet-chamber and adiacent to said first pressure-medium connecting-chamber and is provided with a pressuremedium vent, a second pressure-medium outlet-chamber which is situated opposite said pressure-medium inletchamber and adjacent to said second pressure-medium E connecting-chamber and is provided with a pressuremedium vent, said slide-valve piston in a rst position connecting said first pressure-medium connecting-chamber with said rst pressure-medium-outletchamber and said second pressure-medium connecting chamber With said pressure-medium inlet-chamber, While in a second position said piston connecting said rst pressure-medium connecting-chamber with said pressure-medium inletchamber and said second pressure-medium connecting chamber with said second pressure-medium outlet-chamber, said main valve including diierential pressure oper-A ating means, comprising two pressure chambers cooperating in counteracting relation with two operating surfaces of different size on said Valve piston, said pressure charnbers being connected to said main conduit independently 15 of a pressure medium inlet of said main valve; and means controlling said operating means independently of said pressure medium inlet of said main valve.

References Cited in the le of this patent UNITED STATES PATENTS 471,882 Nanny Mar. 29, 1892 818,284 Pelham Apr. 17, 1906 986,592 Rankin Mar. 14, 1911 10 2,712,302 Zomer July 5, 1955 2,745,429 Crookston May 15, 1956 FOREIGN PATENTS 1,054,297 Germany Apr. 2, 1959 

1. A MAIN CONTROL SLIDE VALVE WHICH IS OPERATED BY DIFFERENTIAL PRESSURE FOR OPERATING A PRESSURE-MEDIUM ENGINE, OF WHICH THE WORKING PISTON IS FED AND DRIVEN BY A PRESSURE-MEDIUM FROM TWO SIDES IN ALTERNATION DURING THE WORKING STROKES, COMPRISING AT LEAST THREE STATIONARY VALVE CHAMBERS FORMED BY AN ANNULAR SPACE BETWEEN THE OUTER SURFACE OF THE FULL DIAMETER ZONES OF A SLIDE VALVE HAVING TWO ZONES OF CONSTRICTED DIAMETER AND THE INNER SURFACE OF A CYLINDRICAL VALVE HOUSING, SAID STATIONARY VALVE CHAMBERS BEING ARRANGED SIDE BY SIDE ALONG THE LONGITUDINAL AXIS OF SAID CYLINDRICAL VALVE HOUSING AND BEING SEPARATED FROM EACH OTHER BY PACKING RINGS SECURED TO THE INNER SURFACE OF THE VALVE HOUSING AND ALTERNATELY ENGAGED AND RELEASED BY SAID FULL DIAMETER ZONES OF THE SLIDE VALVE SO THAT CHAMBERS WHICH ARE IN COMMUNICATION IN A FIRST SLIDE POSITION ARE SEPARATED IN THE SECOND POSITION AND VICE VERSA; AND DIFFERENTIAL PRESSURE MEANS TO MOVE SAID SLIDE VALVE BETWEEN SAID TWO POSITIONS COMPRISING A FIRST PISTON HEAD OF ENLARGED CROSS SECTION ON A FIRST END OF SAID CONTROL SLIDE VALVE, WHICH PISTON HEAD WORKS IN A FIRST OPERATING CHAMBER OF SAID VALVE HOUSING AND A SECOND PISTON HEAD OF SMALLER CROSS SECTION ON A SECOND END OF SAID CONTROL SLIDE, WHICH SECOND PISTON HEAD WORKS IN A SECOND OPERATING-CHAMBER OF SAID VALVE HOUSING AND MEANS INDEPENDENT FROM SAID PRESSURE INLET OF THE VALVE WHICH CONNECT SAID SECOND OPERATING-CYLINDER DIRECTLY WITH PRESSURE-MEDIUM PIPING AT ALL TIMES AND WHICH CONNECT SAID FIRST OPERATING-CYLINDER SELECTIVELY WITH SAID PRESSURE MEDIUM INLET VALVE AND WITH SAID SECOND OPERATING-CYLINDER VIA VALVES, AND CONNECT SELECTIVELY WITH SAID PRESSURE-MEDIUM PIPING AND WITH A PRESSURE-MEDIUM VENT. 